Due to the advantages of self emission, quick response, high brightness, light and thin, an OLED (Organic Light Emitting Diode) display panel has become the mainstream produce in the display field.
The OLED display panel comprises sub-pixel units which are arranged in an array. Each sub-pixel unit comprises an anode, a light emitting layer, and a cathode. The light emitting layer is made from an organic electrolumincent light emitting material form. Currently, the light emitting layer is formed in each sub-pixel unit in an evaporation process with a mask plate. During the evaporation process, the mask plate must be soldered onto the frame so as to be used in the evaporation apparatus. The mask plate and the frame which have been soldered together are referred to as a MFA (mask frame assembly). The alignment mask is prone to introduce liquid residuals during use. The liquid residuals adversely affect the alignment process, and even cause failure in alignment. Thus, it is urgent to solve the problem in which liquid residuals affect the alignment process.